A data centre edge network serves as a boundary to the data centre. The edge network is connected to host devices or servers on one side, and to an edge router that serves as an outgoing interface to an external network on the other side. A first-hop gateway of the edge network may implement a redundancy protocol for establishing a fault-tolerant gateway, such as VRRP (Virtual Router Redundancy Protocol), HSRP (Hot Standby Route Protocol) etc. The fabric core of an edge network may be implemented as a layer 2 virtual private network (L2VPN). In this case, from a global perspective, the L2VPN domain may be viewed as a single virtual device such as a layer 3 switch.
Traffic forwarding within a layer 2 network of a data centre may use any suitable network protocol such as SPB (Shortest Path Bridge), TRILL (Transparent Interconnection of lots of link), VPLS (Virtual Private Label Switch) etc. These techniques support layer 2 traffic forwarding according to ECMP (Equal Cost Multi Path), shortest path and transparent switching. Internal layer 2 traffic forwarding is by way of L2VPN forwarding between physical devices. Layer 2 and layer 3 forwarding is performed via the edge network.